In human anatomy, the biceps brachii, or simply biceps in common parlance, is, as the name implies, a two-headed muscle located on the upper arm. Both heads arise on the scapula and join to form a single muscle belly which is attached to the upper forearm.

In human anatomy, the infraspinatus muscle is a thick triangular muscle, which occupies the chief part of the infraspinatous fossa. As one of the four muscles of the rotator cuff, the main function of the infraspinatus is to externally rotate the arm and stabilize the shoulder joint.

The supraspinatus (plural supraspinati, from Latin supraspinatus) is a relatively small muscle of the upper arm that runs from the supraspinatous fossa superior of the scapula (shoulder blade) to the greater tubercle of the humerus.